I would be furious too, you ordered early and still got all those substitutes!
I have had a bit of a disappointing experience with some dahlia tubers this year, I bought two bags of 8 tubers selected by colour, with the intention of potting them up and taking cuttings. However, out of 16, only 10 grew at all! I decided to take it up with the garden centre I got them from (that I don't usually visit much due to its location), but did not expect to get much joy. They said on the 'phone they had sold out of dahlias now, but come down and they 'would see what they could do'.
To my suprise when I got there they had found three bags of the same dahlias I had purchased , so replaced both bags for me! So I am now potting up another 16 tubers, hope they do a bit better! I am only a novice dahlia grower, just want some flowers for the plots and at home...there is a dahlia 'shower' on our site, and they are fantastic, I have no intentions of trying to compete!